Three-dimensional (3D) display has become the trend of the display field. The principle of 3D display is to generate a stereoscopic image by parallax. That is, a left-eye image is provided to the left eye of an observer, and a right-eye image is provided to the right eye of the observer; the left-eye image and the right-eye image belong to a pair of stereoscopic image with parallax.
3D display techniques based on polarizing glasses is a kind of commonly used 3D display technology. Two images, i.e., left-image and right-image, are projected from the display. The left-image and right-image are respectively distributed to left and right eyes of the user by means of polarizing glasses corresponding to the display. The polarizing glasses employs lenses having different polarizing directions to make the light emitting from the display generate polarizing directions in different angles corresponding to the images.
As shown in FIG. 1, a 2D/3D display device based on polarizing glasses includes: a backlight source 1, a display panel 3, and a patterned retarder 5 interposed between the display panel 3 and the polarizing glasses 6. The display panel 3 can selectively display left-eye images L and right-eye images R, and changes the polarizing directions of the polarizing light with the retarder 5, so that the polarizing light can be received by the polarizing glasses 6. In FIG. 1, a lower polarizing sheet 2 and an upper polarizing sheet 4 are attached to either side of the display panel 3, respectively.
If both the light of the left-eye image and the light of the right-eye image can enter both the left and right eyes, the user will perceive crosstalk. The 3D image visibility on the display device as shown in FIG. 1 is reduced due to the crosstalk at position of the vertical viewing angle. When a user observes the display panel 3 from a lower or upper position instead of from the front, crosstalk will occur at a vertical viewing angle larger than the front viewing angle by a certain angle. The display device has a narrower 3D image viewing angle without crosstalk. In order to increase the vertical viewing angle of the display device shown in FIG. 1, there is another method in which black stripes (BS) are formed on the retarder. As shown in FIG. 2, in such a method, when a user observes the display device at position D which is a certain distance from the display device, the resultant vertical viewing angle α without crosstalk depends on the size of the black matrix (BM) on the display panel 3, the size of the BS, and the distance S between the display panel 3 and the retarder 5. As sizes of the BM and BS and the distance S increase, the vertical viewing angle α increases.
Although the BS increases the vertical viewing angle of the display device to a certain extent, the BS may interact with the BM to generate moiré. Thus, when a 2D image is displayed on the display device, the visibility of the 2D image is greatly reduced due to the moiré. In addition, since the BS are formed at positions of the retarder 5 corresponding to pixels of the display panel 3, when a 2D image is displayed on the 3D display device, the luminance of the 2D image may be also reduced due to the BS.